Makes the opponent kill himself. One-two drop combo sleeper agent -> wall of souls. Every turn 2 life lost for opponent. Can't attack with 3/3 since it will just be blocked by wall (= 3 extra life lost).

Feast on the fallen + sleeper agent. Almost guaranteed damage each turn.
treacherous pit-dweller (4/3) strong 2 drop. Put counter on via feast on the fallen, or slitherhead to prevent it from reaching the opponent when it dies.
Feast of the fallen makes sure slitherhead is in graveyard, or you can sacrifice treacherous pit-dweller when nessecary.

+ Wall of Souls
+ Opponent self-destruction theme
- Opponent sacs own creatures.

Sideboard option preventing activated abilities of all creatures.